Negative electrode composition for lithium ion secondary battery, negative electrode slurry, negative electrode, and lithium ion secondary battery

Abstract

The present application relates to a negative electrode composition for a lithium ion secondary battery, which contains a negative electrode active material, a conductive material, and an aqueous binder, and which is characterized in that the conductive material contains a pre-dispersed liquid containing a specific type of dispersant, and the aqueous binder contains a specific content of (meth) acrylamide (AM). In addition, the present application relates to a negative electrode slurry containing the negative electrode composition for a lithium ion secondary battery, a negative electrode for a lithium ion secondary battery, and a lithium ion secondary battery. The negative electrode composition for a lithium ion secondary battery may contribute to improving phase stability and suppressing volume expansion due to battery charging and discharging.

Description

[Technical Field]

[0001] The present application relates to a negative electrode composition for a lithium ion secondary battery, a negative electrode slurry, a negative electrode, and a lithium ion secondary battery.

[0002] This application claims the priority and benefits of Korean Patent Application Nos. 10-2023-0042670 and 10-2024-0042404, filed with the Korean Intellectual Property Office on March 31, 2023 and March 28, 2024, respectively, the entire contents of which are incorporated herein by reference. [Background Art]

[0003] Due to the rapid increase in the use of fossil fuels, the demand for alternative or clean energy is increasing day by day. As part of this trend, the most actively studied field is the field of power generation and power storage using electrochemical reactions.

[0004] Currently, representative examples of electrochemical devices using such electrochemical energy include secondary batteries, and their fields of use are increasing.

[0005] Meanwhile, with the development of technology and the increasing demand for mobile devices, the demand for secondary batteries has also increased rapidly. Therefore, lithium ion secondary batteries having characteristics such as high energy density and voltage, long cycle life, and low self-discharge rate have been commercialized and widely used. Therefore, as an electrode for a high-capacity lithium ion secondary battery, research has been actively conducted to prepare an electrode having a higher energy density per unit volume.

[0006] Generally, a secondary battery is composed of a positive electrode, a negative electrode, an electrolyte, and a separator. Specifically, the negative electrode includes a negative electrode active material, and silicon-based particles having a large charge-discharge capacity can be used as the negative electrode active material.

[0007] In particular, recently, due to the demand for secondary batteries with high-energy electrodes, research has been actively conducted on methods for increasing the capacity by using silicon-based compounds such as Si / C, SiO x (x = 0) or SiO x (0 < x < 2) etc. as the negative electrode active material. However, compared with existing graphite-based materials, silicon-based compounds have the following problems: due to the generation of hydrogen during repeated charge and discharge processes, volume expansion occurs, blocking the conductive path, resulting in deterioration of battery characteristics.

[0008] In order to solve the volume expansion caused by the above-mentioned repeated charge and discharge processes, research has also been conducted on the composition of the binder. As a result, research has been conducted on binder polymers having strong stress. However, these binder polymers themselves have limitations in preventing an increase in electrode thickness caused by the shrinkage and expansion of the negative electrode active material and the resulting deterioration in the performance of the lithium ion secondary battery.

[0009] In addition, in order to ensure the conductivity of the negative electrode, the secondary battery also includes a conductive material. Although carbon black and the like are mainly used in the prior art, in order to improve the capacity of the secondary battery, single-walled carbon nanotubes (SWCNTs) having an elongated shape have been used.

[0010] However, when single-walled carbon nanotubes are used as a conductive material, they need to be used in the form of a single-walled carbon nanotube dispersion so that the single-walled carbon nanotubes are uniformly arranged in the active material layer. However, as the dispersion degree of the dispersion increases, the density difference between the conductive material containing the dispersion and the active material deepens, resulting in the migration of the conductive material from the collector to the upper layer, thereby causing problems such as deterioration of the phase stability and conductivity of the negative electrode composition.

[0011] Therefore, in order to improve battery characteristics while controlling the dispersion of SWCNTs, various methods are being studied in terms of changing the constituent components of the negative electrode composition. [Summary of the invention]

[0012] [Technical issues]

[0013] The inventors have found that by using single-walled carbon nanotubes (SWCNTs) as conductive materials, using non-ionic vinyl compounds as dispersants to control the compatibility and dispersibility with conductive materials, and using an aqueous binder containing a specific content of (meth)acrylamide to further improve the dispersibility, the volume expansion problem of the negative electrode, the cycle performance problem, etc. can ultimately be solved.

[0014] The present specification is dedicated to providing a negative electrode composition for a lithium ion secondary battery, and a negative electrode slurry, a negative electrode and a lithium ion secondary battery comprising the negative electrode composition, wherein the dispersibility of single-walled carbon nanotubes is controlled by using a specific type of dispersant and an aqueous binder containing a specific content of (meth)acrylamide, thereby improving the volume expansion problem of the negative electrode.

[0015] [Technical solution]

[0016] An exemplary embodiment of the present specification provides a negative electrode composition for a lithium ion secondary battery, comprising a negative electrode active material, a conductive material and an aqueous binder, wherein the conductive material comprises a pre-dispersion liquid containing single-walled carbon nanotubes (SWCNTs) and a dispersant, the aqueous binder comprises 30 wt % or more and 80 wt % or less of (meth)acrylamide (AM) relative to 100 wt % of the total aqueous binder, and the dispersant comprises a nonionic vinyl compound.

[0017] In another exemplary embodiment, provided is a negative electrode slurry including the negative electrode composition for a lithium ion secondary battery and a solvent.

[0018] In yet another exemplary embodiment, an electrode is provided, comprising: a current collector layer; and a negative electrode active material layer disposed on one surface or both surfaces of the current collector layer, wherein the negative electrode active material layer comprises the negative electrode slurry or a dried product thereof.

[0019] Finally, a lithium ion secondary battery is provided, which includes: a first electrode; a second electrode; a separator inserted between the first electrode and the second electrode; and an electrolyte, wherein any one of the first electrode and the second electrode is the negative electrode.

[0020] [Beneficial Effects]

[0021] The negative electrode composition for lithium ion secondary batteries of the exemplary embodiment of the present invention controls the dispersibility of single-walled carbon nanotubes in the conductive material, uses an aqueous binder containing (meth)acrylamide with high strength characteristics to improve the compatibility and / or phase stability between the conductive material and the aqueous binder, and prevents the volume expansion of the negative electrode active material, so as to provide a lithium ion secondary battery with high performance and long life characteristics in the future.

[0022] In addition, since the negative electrode slurry, the negative electrode, and the lithium ion secondary battery according to the exemplary embodiment of the present invention include the negative electrode composition for a lithium ion secondary battery, the above-mentioned effects can be exhibited as is, so that the safety and stability of the lithium ion secondary battery can be ensured. [Specific implementation method]

[0023] Before describing the present invention, some terms are first defined.

[0024] When a part of the present specification “comprises” one component, unless otherwise specifically stated, this does not mean that other components are excluded but means that other components may further be included.

[0025] In this specification, "p to q" means a range of "p or more and q or less".

[0026] In the present specification, when x parts by weight is based on 100 parts by weight, weight % may also be used for the unit.

[0027] In the present specification, a polymer containing a certain monomer as a repeating unit means that the monomer participates in a polymerization reaction and is contained in the polymer as a repeating unit.

[0028] In the present specification, when a polymer comprises a monomer, this is understood to be the same as when the polymer comprises a monomer as a monomer unit.

[0029] In this specification, "polymer" should be understood to be used in a broad sense, including copolymers, unless otherwise specified as a "homopolymer".

[0030] In this specification, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are polystyrene-equivalent molecular weights measured by gel permeation chromatography (GPC) using commercially available monodisperse polystyrene polymers (standard samples) having various polymerization degrees for measuring molecular weight as standard substances.

[0031] In this specification, unless otherwise specified, the molecular weight refers to the weight average molecular weight.

[0032] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in various forms and is not limited to the following description.

[0033] <Negative electrode composition for lithium ion secondary battery>

[0034] An exemplary embodiment of the present specification provides a negative electrode composition for a lithium ion secondary battery, comprising a negative electrode active material, a conductive material and an aqueous binder, wherein the conductive material comprises a pre-dispersion liquid containing single-walled carbon nanotubes (SWCNTs) and a dispersant, the aqueous binder comprises 30 wt % or more and 80 wt % or less of (meth)acrylamide (AM) relative to 100 wt % of the total aqueous binder, and the dispersant comprises a nonionic vinyl compound.

[0035] The negative electrode composition for lithium ion secondary batteries of the exemplary embodiment of the present invention controls the dispersibility of single-walled carbon nanotubes in the conductive material, uses an aqueous binder containing (meth)acrylamide with high strength characteristics to improve the compatibility and / or phase stability between the conductive material and the aqueous binder, and prevents the volume expansion of the negative electrode active material, so as to provide a lithium ion secondary battery with high performance and long life characteristics in the future.

[0036] The negative electrode composition for a lithium ion secondary battery according to the exemplary embodiment can improve phase stability and mechanical properties by satisfying the content range of (meth)acrylamide as the first repeating unit, and further improve cycle and / or life performance in future batteries.

[0037] In the present specification, the term "(meth)acrylamide" may include methacrylamide or acrylamide.

[0038] In the present specification, the aqueous adhesive may contain (meth)acrylic acid (AA) in addition to (meth)acrylamide.

[0039] In the present specification, the aqueous adhesive may contain (meth)acrylonitrile in addition to (meth)acrylamide and (meth)acrylic acid.

[0040] In this specification, the aqueous adhesive refers to an adhesive based on water as a solvent or an electrolyte.

[0041] In the present specification, unless otherwise specified, the aqueous adhesive refers to a copolymer including two or more repeating units.

[0042] In the present specification, unless otherwise specified, the copolymer is a concept including all of alternating copolymers, random copolymers, block copolymers and graft copolymers.

[0043] According to an exemplary embodiment of the present specification, the pre-dispersion liquid may contain: relative to 100 parts by weight of all single-walled carbon nanotubes, more than 0 parts by weight and less than 1 part by weight of single-walled carbon nanotubes having a length greater than 0 μm and less than 0.2 μm, and more than 15 parts by weight of single-walled carbon nanotubes having a length greater than 10 μm and less than 100 μm.

[0044] The negative electrode composition for lithium ion secondary batteries of this exemplary embodiment can control dispersibility and effectively improve conductivity. Specifically, when the amount of single-walled carbon nanotubes with a length greater than 0 μm and less than 0.2 μm relative to 100 parts by weight of all single-walled carbon nanotubes is less than 1 part by weight, damage to the single-walled carbon nanotubes caused by excessive pre-dispersion can be suppressed, and the connectivity of the conductive network can be prevented from deteriorating, and as long as the content of single-walled carbon nanotubes with a length of more than 10 μm and less than 100 μm relative to 100 parts by weight of all single-walled carbon nanotubes satisfies 15 parts by weight or more, during the charge and discharge process, the volume expansion of the electrode during the charge and discharge process makes the connectivity of the conductive network excellent, so the life can be improved.

[0045] In the present specification, the preliminary dispersion can be prepared by adding the single-walled carbon nanotubes and a dispersant (in addition, a dispersion medium, a viscosity modifier, etc.) and mixing the resulting mixture, and then grinding the mixture.

[0046] In the present specification, the pre-dispersion liquid is prepared by a method of preparing single-walled carbon nanotubes and then preparing the pre-dispersion liquid using a high-pressure homogenizer or the like.

[0047] In this specification, "100 parts by weight of all single-walled carbon nanotubes" refers to the solid content, in other words, the solid content of the pre-dispersion liquid. The weight basis of the solid content and the solid content of each component can be measured by general analytical means used in the art, such as liquid chromatography or gas chromatography.

[0048] In the present specification, grinding can be performed by a ball mill, a bead mill, a disc mill, a basket mill or a high-pressure homogenizer. Preferably, a high-pressure homogenizer can be used because it can effectively disperse the single-walled carbon nanotubes without damaging them.

[0049] In this specification, grinding by a high pressure homogenizer can be performed by pressurizing the mixture using, for example, a plunger pump of the high pressure homogenizer, pushing the mixture into a gap of a homogenizing valve, and utilizing forces such as cavitation, shearing, impact and explosion when the mixture passes through the gap.

[0050] In this specification, the particle size of single-walled carbon nanotubes (SWCNTs) can be measured by a particle size analyzer (manufactured by Malvern Panalytical Ltd.) using a laser diffraction method. The laser diffraction method is generally capable of measuring particle sizes (particularly lengths) in a wide range from submicrometers to several millimeters, and can obtain highly reproducible and high-resolution analysis results.

[0051] In an exemplary embodiment of the present specification, the negative electrode active material may include one or more selected from the group consisting of a silicon-based active material and a carbon-based active material.

[0052] In another exemplary embodiment of the present specification, the negative electrode active material may be a silicon-based active material.

[0053] By including a silicon-based active material as a negative electrode active material, the negative electrode composition for a lithium ion secondary battery of this exemplary embodiment can have a capacity more than 10 times higher than that of a carbon-based active material. Therefore, when a silicon-based active material is applied to a negative electrode, a thinner electrode with a higher level of energy density can be achieved compared to a single carbon-based active material.

[0054] In still another exemplary embodiment of the present specification, the negative electrode active material may include a silicon-based active material and a carbon-based active material.

[0055] In still another exemplary embodiment of the present specification, when the negative electrode active material includes a silicon-based active material and a carbon-based active material, a weight ratio of the silicon-based active material to the carbon-based active material may be 2:98 to 30:70.

[0056] The negative electrode active material of this exemplary embodiment includes a carbon-based active material as a main component, and thus can further provide an effect that the negative electrode is excellent in conductive connectivity due to slight swelling of the active material due to small volume expansion during charge and discharge.

[0057] In an exemplary embodiment of the present specification, the silicon-based active material may include SiO x (x=0),SiOx One or more of (0 < x < 2), SiC, and Si alloy.

[0058] In this specification, SiO is not included. x In SiO where x is 2 2 In the case of this SiO 2 Does not react with lithium ions and thus cannot store lithium. Therefore, it is preferred that x falls within the range of the exemplary embodiments.

[0059] In this specification, the silicon-based active material can be Si / C composed of a composite of Si and C, or Si.

[0060] In this specification, two or more silicon-based active materials can be used in combination.

[0061] In one exemplary embodiment of this specification, based on 100 parts by weight of the negative electrode composition for a lithium ion secondary battery, the amount of the negative electrode active material present can be 60 parts by weight or more.

[0062] In one exemplary embodiment of this specification, based on 100 parts by weight of the negative electrode composition for a lithium ion secondary battery, the amount of the negative electrode active material present can be 60 parts by weight or more, preferably 65 parts by weight or more, more preferably 70 parts by weight or more, and 95 parts by weight or less, preferably 90 parts by weight or less.

[0063] In this specification, the silicon-based active material can exist, for example, in crystalline or amorphous form. Specifically, the silicon particles of the silicon-based active material can preferably be spherical particles, but are not limited thereto.

[0064] In one exemplary embodiment of this specification, when the negative electrode active material consists only of the silicon-based active material, the silicon-based active material includes one or more selected from the group consisting of SiO x (x = 0) and SiO x (0 < x < 2), and based on 100 parts by weight of the silicon-based active material, it can contain 70 parts by weight or more of SiO x (x = 0).

[0065] In another exemplary embodiment, based on 100 parts by weight of the silicon-based active material, the content of SiO x (x = 0) in the silicon-based active material can be 70 parts by weight or more, preferably 80 parts by weight or more, more preferably 90 parts by weight or more, or 100 parts by weight or less, preferably 99 parts by weight or less, more preferably 95 parts by weight or less.

[0066] In another exemplary embodiment of the present invention, when the silicon-based active material contains SiO x (x = 0), SiOx The average particle size (D 50 ) can be 3μm to 10μm.

[0067] When the above range is satisfied, it is possible to ensure that the active material is structurally stable during charge and discharge, and to prevent the problem of increasing the volume expansion / contraction level due to excessive increase in particle size and the problem of reducing initial efficiency due to excessively small particle size.

[0068] The particle size of the negative electrode active material can be adjusted by a ball mill, a jet mill, or an air flow classification method, but the method is not limited thereto.

[0069] In this manual, "D n " represents the particle size distribution, which refers to the particle size at the n% point in the cumulative distribution of the number of particles according to the particle size. That is, D 50 D is the particle size at the 50% point in the cumulative distribution of the number of particles according to the particle size (average particle size), 90 is the particle size at the 90% point in the cumulative distribution of the number of particles according to the particle size, D 10 The particle size distribution is the particle size at the 10% point in the cumulative distribution of the number of particles according to the particle size. Meanwhile, the particle size distribution can be measured using a laser diffraction method. Specifically, after the powder to be tested is dispersed in a dispersion medium, the particle size distribution is calculated by introducing the obtained dispersion into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500) to measure the difference in the diffraction pattern that changes with the particle size when the particles pass through the laser beam.

[0070] In an exemplary embodiment of the present specification, the carbon-based material may include at least one selected from the group consisting of artificial graphite, natural graphite, hard carbon, and soft carbon.

[0071] In an exemplary embodiment of the present specification, the conductive material may be present in an amount of 0.03 parts by weight or more and 40 parts by weight or less based on 100 parts by weight of the negative electrode composition.

[0072] In another exemplary embodiment of the present specification, the content of the conductive material may be 0.03 parts by weight or more and 40 parts by weight or less, preferably 0.05 parts by weight or more and 30 parts by weight or less, and more preferably 0.5 parts by weight or more and 25 parts by weight or less, based on 100 parts by weight of the negative electrode composition.

[0073] In the present specification, the conductive material and the aqueous binder contained in the negative electrode composition for lithium ion secondary batteries may refer to the negative electrode conductive material and the negative electrode aqueous binder, respectively.

[0074] In this specification, the negative electrode conductive material has a completely different structure from the positive electrode conductive material used for the positive electrode. That is, the negative electrode conductive material of the present application plays a role in capturing the contact points between the silicon-based active materials whose volume expansion is very large due to charge and discharge, and the positive electrode conductive material plays a role in providing partial conductivity while playing a buffering role during rolling. Its structure and role are completely different from those of the negative electrode conductive material of the present invention.

[0075] In addition, when the negative electrode active material includes a silicon-based active material, the negative electrode conductive material of the present application may have a completely different composition from the conductive material used for the graphite-based active material (i.e., only graphite in the carbon-based active material). That is, the conductive material used for the negative electrode having the graphite-based active material simply has small particles relative to the active material, thereby having the characteristics of improving the output characteristics and imparting partial conductivity, and its composition and function are completely different from the negative electrode conductive material used together with the silicon-based active material in the present invention.

[0076] In this specification, using a carbon-based active material as an active material means processing the carbon-based active material into a dot shape or a spherical shape and using it as a material that plays a role in storing or releasing lithium.

[0077] That is, in an exemplary embodiment of the present application, artificial graphite or natural graphite as a carbon-based active material is in a dot-like form, and its BET specific surface area can satisfy 0.1 m 2 / g or more and 4.5m 2 In addition, the plate-like graphite as a planar conductive material is in a planar form, and its BET specific surface area can be 5m 2 / g or above.

[0078] In an exemplary embodiment of the present invention, the nonionic vinyl compound may be one or more selected from the group consisting of polyvinyl pyrrolidone (PVP) and polyvinyl butyral (PVB). Preferably, the dispersant may be polyvinyl pyrrolidone (PVP).

[0079] When the above dispersant is used in the negative electrode composition for a lithium ion secondary battery, the phase stability in the future preparation of the negative electrode slurry is improved, and thus the life performance of the negative electrode including the negative electrode slurry can be improved.

[0080] In particular, among nonionic vinyl compounds, PVP has excellent solubility in water and excellent mutual adhesion strength with SWCNTs, and can respond to changes in pH depending on the composition of the slurry with the type and content of the aqueous binder and the conductive material, and has excellent characteristics in phase stability because PVP is insensitive to interaction with single-walled carbon nanotubes (SWCNTs).

[0081] In another embodiment of the present invention, the dispersant may further comprise an elastomer, such as hydrogenated nitrile rubber (H-NBR).

[0082] In an exemplary embodiment of the present invention, the dispersant may be present in an amount of 0.5 parts by weight or more and 5 parts by weight or less based on 100 parts by weight of the negative electrode composition.

[0083] In another exemplary embodiment of the present invention, a dispersant is used to disperse the SWCNT conductive material, and its upper limit is not particularly limited. The dispersant can be used to the extent that the dispersant does not affect the physical properties of the adhesive. Preferably, the upper limit is preferably 20 parts by weight or less, or 10 parts by weight or less relative to 100 parts by weight of the adhesive. The lower limit of the dispersant is preferably 20 parts by weight or more, preferably 50 parts by weight or more, 100 parts by weight or more, and preferably 150 parts by weight or more relative to 100 parts by weight of SWCNT. When the amount of the dispersant present based on 100 parts by weight of SWCNT is less than 20 parts by weight, it may be difficult to effectively disperse the SWCNT, and the dispersion stability after dispersion may be deteriorated.

[0084] In an exemplary embodiment of the present invention, the aqueous adhesive may be a copolymer including (meth)acrylamide (AM) as a first repeating unit and (meth)acrylic acid (AA) as a second repeating unit.

[0085] When the copolymer is contained as an aqueous binder, solubility in a solvent (a solvent used when preparing a slurry) can be further improved.

[0086] In another exemplary embodiment of the present invention, when the aqueous adhesive is a copolymer consisting of two repeating units of (meth)acrylamide (AM) and (meth)acrylic acid (AA), the weight ratio of AM:AA may be 30-80:20-70.

[0087] When the weight ratio is satisfied, the aqueous binder can ensure improved mechanical properties and cycle characteristics, and can control the dispersibility with single-walled carbon nanotubes (SWCNTs). In addition, when the weight ratio is satisfied, the aqueous binder can additionally improve solubility in a solvent (e.g., water used as a solvent when preparing the slurry).

[0088] In an exemplary embodiment of the present invention, the aqueous adhesive may be a copolymer further comprising (meth) acrylonitrile (AN) as a third repeating unit. In other words, the aqueous adhesive may be a copolymer comprising a first repeating unit derived from (meth) acrylamide (AM), a second repeating unit derived from (meth) acrylic acid (AA), and a third repeating unit derived from (meth) acrylonitrile (AN).

[0089] According to this exemplary embodiment, solubility and / or dispersibility in a solvent (a solvent used when preparing the slurry) may be additionally improved, and adhesion may be additionally improved.

[0090] In another exemplary embodiment of the present invention, when the aqueous adhesive is a terpolymer comprising three repeating units of (meth)acrylamide (AM), (meth)acrylic acid (AA) and (meth)acrylonitrile (AN), the weight ratio of AM:AA:AN may be 30 to 80:10 to 40:10 to 30.

[0091] Since the aqueous adhesive satisfying the above weight ratio can ensure improved mechanical properties and cycle characteristics and control the dispersibility with single-walled carbon nanotubes (SWCNTs), network connectivity can be improved. In addition, the aqueous adhesive satisfying the above weight ratio can also improve solubility in a solvent (e.g., water used as a solvent when preparing the slurry). In addition, when the above weight ratio is satisfied, adhesion characteristics can be improved.

[0092] In the present specification, a polymerization initiator is used to prepare the aqueous binder (copolymer), and ammonium persulfate may be used as an example of the polymerization initiator, but the polymerization initiator is not limited thereto.

[0093] In the present specification, in order to prepare the aqueous adhesive, the copolymer is first prepared and then may be neutralized with an acid or a base of a predetermined concentration as necessary.

[0094] In an exemplary embodiment of the present specification, the aqueous binder may be present in an amount of 2 parts by weight or more and 30 parts by weight or less based on 100 parts by weight of the negative electrode composition.

[0095] In another exemplary embodiment of the present specification, the content of the aqueous binder may be 30 parts by weight or less, preferably 25 parts by weight or less, more preferably 20 parts by weight or less, or the content may be 2 parts by weight or more, 5 parts by weight or more, or 10 parts by weight or more, based on 100 parts by weight of the negative electrode composition.

[0096] In still another exemplary embodiment of the present specification, the weight average molecular weight of the binder may be 100,000 g / mol or more and 1,500,000 g / mol or less.

[0097] The negative electrode composition of this exemplary embodiment can ensure the following characteristics: since the weight average molecular weight of the binder satisfies the above range, the mechanical strength is excellent, and since the interaction between molecules is improved, the adhesion strength of the negative electrode is excellent. In addition, when the above range is satisfied, the viscosity of the aqueous binder can be controlled within an appropriate range, so that when the negative electrode is manufactured using the binder, the negative electrode has the characteristic of excellent coating properties.

[0098] <Method for preparing negative electrode composition for lithium ion secondary battery>

[0099] An exemplary embodiment of the present invention provides a method for preparing a negative electrode composition for a lithium ion secondary battery, the method comprising: preparing a pre-dispersion liquid by dispersing single-walled carbon nanotubes (SWCNTs) as a conductive material and a dispersant; mixing an aqueous binder containing 30 wt % or more and 80 wt % or less of (meth)acrylamide (AM) relative to 100 wt % of the entire aqueous binder with the conductive material; and adding a negative electrode active material thereto and mixing the resulting mixture, wherein the dispersant contains a nonionic vinyl compound.

[0100] In the present specification, the preliminary dispersion is prepared by a method in which single-walled carbon nanotubes and a dispersant are prepared and then the preliminary dispersion is prepared using a high-pressure homogenizer or the like.

[0101] The specific contents of the components in the method for preparing the negative electrode composition for lithium ion secondary battery are as described above.

[0102] According to the method for preparing a negative electrode composition for a lithium ion secondary battery of this exemplary embodiment, the dispersibility of the conductive material is controlled and the morphology of the single-walled carbon nanotube structure formed by dispersion is easily maintained, thereby improving phase stability and improving the life characteristics of future batteries.

[0103] <Negative electrode slurry>

[0104] In an exemplary embodiment of the present invention, a negative electrode slurry is provided, which includes the negative electrode composition for a lithium ion secondary battery and a solvent.

[0105] In an exemplary embodiment of the present invention, the solvent may be water, but is not limited thereto.

[0106] In the present specification, the solvent may be a solvent that can be combined with the negative electrode composition.

[0107] In some cases, when in addition to appropriately adjusting the average particle size (D 50 ) In addition to the above, by appropriately adjusting the specific surface area of ​​the particles and controlling the viscosity of the negative electrode slurry within a suitable range, the dispersion of the constituent components (e.g., conductive materials, binders, silicon-based active materials, etc.) in the slurry can be improved. Thus, the contact area between the constituent components is improved, so that the conductive network can be maintained, the capacity retention rate can be improved, and the current density non-uniformity during charging / discharging can be prevented.

[0108] <Negative electrode>

[0109] Another exemplary embodiment of the present invention provides a negative electrode including: a current collector layer; and a negative electrode active material layer disposed on one surface or both surfaces of the current collector layer, wherein the negative electrode active material layer includes the negative electrode slurry or a dried product thereof.

[0110] In this specification, unless otherwise limited, the collector layer of the negative electrode may be referred to as a negative electrode collector layer.

[0111] In an exemplary embodiment of the present application, the solid content of the negative electrode slurry may satisfy 3 wt % or more and 50 wt % or less.

[0112] In another exemplary embodiment, the solid content of the negative electrode slurry may satisfy the range of 3 wt % to 50 wt %, preferably 5 wt % to 45 wt %, and more preferably 7 wt % to 40 wt %.

[0113] The solid content of the negative electrode slurry may refer to the content of the negative electrode composition contained in the negative electrode slurry, and may refer to the content of the negative electrode composition based on 100 parts by weight of the negative electrode slurry.

[0114] When the solid content of the negative electrode slurry satisfies the above range, the present invention has a feature of being able to efficiently form a negative electrode active material layer by minimizing the particle aggregation phenomenon of the negative electrode composition due to appropriate viscosity when forming the negative electrode active material layer.

[0115] In an exemplary embodiment of the present application, the slurry solvent may be used without limitation as long as the slurry solvent can dissolve the negative electrode composition, and specifically, water or NMP may be used.

[0116] In the exemplary embodiment of the present application, the thickness of the negative electrode collector layer is generally 1 μm to 100 μm. The negative electrode collector layer is not particularly limited, as long as the negative electrode collector layer has high conductivity and does not cause chemical changes to the battery. For example, copper, stainless steel, aluminum, nickel, titanium, sintered carbon, materials with surface treatment of copper or stainless steel with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloys, etc. can be used. In addition, the negative electrode collector layer can also improve the bonding strength of the negative electrode active material by forming fine concave and convex on its surface. The negative electrode collector layer can be used in various forms, such as films, sheets, foils, nets, porous bodies, foams, and non-woven fabrics.

[0117] In an exemplary embodiment of the present application, there is provided a negative electrode for a lithium ion secondary battery, wherein the thickness of the negative electrode collector layer is 1 μm or more and 100 μm or less, and the thickness of the negative electrode active material layer is 20 μm or more and 500 μm or less.

[0118] However, the thickness may be variously modified depending on the type and purpose of the negative electrode used, without being limited thereto.

[0119] In an exemplary embodiment of the present application, the porosity of the negative electrode active material layer may satisfy a range of 10% or more and 60% or less.

[0120] In another exemplary embodiment, the porosity of the negative electrode active material layer may satisfy the range of 10% or more and 60% or less, preferably 20% or more and 50% or less, and more preferably 30% or more and 45% or less.

[0121] The porosity varies with the composition and content of the silicon-based active material, conductive material and binder contained in the negative electrode active material layer. In particular, when the silicon-based active material and conductive material of the present application are contained in a specific composition and content, the above-mentioned range is satisfied, and thus it is characterized in that the conductivity and resistance in the negative electrode have an appropriate range.

[0122] <Lithium-ion secondary battery>

[0123] In an exemplary embodiment of the present invention, a lithium ion secondary battery is provided, comprising: a first electrode; a second electrode; a separator interposed between the first electrode and the second electrode; and an electrolyte, wherein any one of the first electrode and the second electrode is the negative electrode.

[0124] In this specification, the first electrode may be a positive electrode, and the second electrode may be a negative electrode, or vice versa.

[0125] A secondary battery of an exemplary embodiment of the present specification may specifically include the above-mentioned negative electrode for lithium-ion secondary batteries. Specifically, the secondary battery may include a negative electrode, a positive electrode, a separator inserted between the positive electrode and the negative electrode, and an electrolyte, and the negative electrode is the same as the above-mentioned negative electrode. Since the negative electrode has been described in detail, its specific description is omitted.

[0126] The positive electrode may include a positive electrode collector and a positive electrode active material layer formed on the positive electrode collector and including a positive electrode active material.

[0127] In the positive electrode, the positive electrode collector is not particularly limited as long as the positive electrode collector has conductivity and does not cause chemical changes to the battery. For example, stainless steel, aluminum, nickel, titanium, sintered carbon, or a material having a surface treated with carbon, nickel, titanium, silver, etc. on the surface of aluminum or stainless steel can be used. In addition, the thickness of the positive electrode collector can generally be 3 μm to 500 μm, and the adhesion of the positive electrode active material can also be improved by forming fine concavoconvexities on the surface of the collector. For example, the positive electrode collector layer can be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, and a non-woven fabric.

[0128] The positive electrode active material may be a commonly used positive electrode active material. Specifically, the positive electrode active material includes: a layered compound, such as lithium cobalt oxide (LiCoO 2 ) and lithium nickel oxide (LiNiO 2 ), or compounds substituted with one or more transition metals; lithium iron oxides, such as LiFe 3 O 4 ; Lithium manganese oxide, such as the chemical formula Li 1+c1 Mn 2-c1 O 4 (0≤c1≤0.33), LiMnO 3 、LiMn 2 O 3 and LiMnO 2 ; Lithium copper oxide (Li 2 CuO 2 ); Vanadium oxides, such as LiV 3 O 8 、V 2 O 5 and Cu 2 V 2 O 7 ; Chemical formula LiNi 1-c2 M c2 O 2 (herein, M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B and Ga, and c2 satisfies 0.01≤c2≤0.3) represented by Ni-type lithium nickel oxide; chemical formula LiMn 2-c3 M c3 O 2 (herein, M is at least any one selected from the group consisting of Co, Ni, Fe, Cr, Zn and Ta, and c3 satisfies 0.01≤c3≤0.1) or Li 2 Mn 3 MO 8 (herein, M is at least one selected from the group consisting of Fe, Co, Ni, Cu and Zn) represented by a lithium-manganese composite oxide; Li in the chemical formula is partially replaced by alkaline earth metal ions LiMn 2 O 4 The positive electrode may be lithium metal.

[0129] The positive electrode active material layer may include a positive electrode conductive material and a positive electrode binder together with the above-mentioned positive electrode active material.

[0130] In this case, the positive electrode conductive material is used to impart conductivity to the positive electrode, and can be used without particular limitation, as long as the positive electrode conductive material has electronic conductivity and does not cause chemical changes in the constituted battery. Specific examples thereof include: graphite, such as natural graphite or artificial graphite; carbon-based materials, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powder or metal fiber, such as copper, nickel, aluminum, and silver; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; or conductive polymers, such as polyphenylene derivatives, any one of which or a mixture of two or more thereof can be used.

[0131] Alternatively, the positive electrode binder is used to improve the bonding between the positive electrode active material particles and the adhesion between the positive electrode active material and the positive electrode collector. Specific examples thereof may include: polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene propylene diene rubber (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluororubber or various copolymers thereof, any one of which or a mixture of two or more thereof may be used.

[0132] The separator separates the negative electrode from the positive electrode and provides a channel for lithium ions to move, and can be used without particular limitation, as long as the separator is generally used as a separator in a secondary battery, in particular, preferably with excellent ability to retain electrolyte moisture and a separator with low resistance to ion movement in the electrolyte. Specifically, a porous polymer film can be used, for example, a porous polymer film formed by a polyolefin polymer (such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer), or a laminated structure of more than two layers thereof. In addition, a typical porous nonwoven fabric can also be used, for example, a nonwoven fabric made of glass fiber, polyethylene terephthalate fiber, etc. with a high melting point. In addition, a coated separator comprising a ceramic component or a polymer material can be used to ensure heat resistance or mechanical strength, and can be selectively used as a single layer or multilayer structure.

[0133] Examples of the electrolyte include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium ion secondary batteries, but are not limited thereto.

[0134] Specifically, the electrolyte may include a non-aqueous organic solvent and a metal salt.

[0135] As the nonaqueous organic solvent, for example, an aprotic organic solvent such as N-methyl-2-pyrrolidone (NMP), propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl propionate and ethyl propionate can be used.

[0136] In particular, among carbonate organic solvents, cyclic carbonates ethylene carbonate and propylene carbonate can be preferably used because cyclic carbonates have a high dielectric constant as a high-viscosity organic solvent and thus dissociate lithium salts well, and because cyclic carbonates can be mixed with low-viscosity and low-dielectric-constant chain carbonates such as dimethyl carbonate and diethyl carbonate in an appropriate ratio and used to prepare an electrolyte with high conductivity, such cyclic carbonates can be more preferably used.

[0137] As the metal salt, a lithium salt can be used. The lithium salt is a material that is easily soluble in a non-aqueous electrolyte. For example, as the anion of the lithium salt, a metal salt selected from the group consisting of F - , Cl - ,I - 、NO 3 - 、N(CN) 2 - , BF 4 - , ClO 4 - PF 6 - ,(CF 3 ) 2 PF 4 - ,(CF 3 ) 3 PF 3 - ,(CF 3 ) 4 PF 2 - ,(CF 3 ) 5 PF - ,(CF 3 ) 6 P - CF 3 SO 3 - CF 3CF 2 SO 3 - ,(CF 3 SO 2 ) 2 N - 、(FSO 2 ) 2 N - CF 3 CF 2 (CF 3 ) 2 CO - ,(CF 3 SO 2 ) 2 CH - , (SF 5 ) 3 C - ,(CF 3 SO 2 ) 3 C - CF 3 (CF 2 ) 7 SO 3 - CF 3 CO 2 - , CH 3 CO 2 - 、SCN - and (CF 3 CF 2 SO 2 ) 2 N - One or more of the groups.

[0138] In the electrolyte, in order to improve the life characteristics of the battery, inhibit the reduction of the battery capacity and increase the discharge capacity of the battery, in addition to the above-mentioned electrolyte components, one or more additives may be further included, such as halogenated alkylene carbonate compounds (such as difluoroethylene carbonate), pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, n-glycol ether, hexamethylphosphoric triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol or aluminum chloride.

[0139] An exemplary embodiment of the present invention provides a battery module including the secondary battery as a unit cell and a battery pack including the battery module. The battery module and the battery include a secondary battery having high capacity, high rate limit characteristics and cycle characteristics, and thus can be used as a power source for medium and large-sized equipment selected from the group consisting of electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage systems.

[0140] <Method for producing lithium-ion secondary battery>

[0141] In another exemplary embodiment of the present invention, a method for manufacturing a lithium ion secondary battery is provided, the method comprising: preparing a negative electrode slurry by mixing a negative electrode composition for a lithium ion secondary battery with a solvent; coating the negative electrode slurry on one surface or both surfaces of a collector layer; and drying the collector layer coated with the negative electrode slurry, the negative electrode composition for a lithium ion secondary battery, the negative electrode slurry, the solvent, the collector layer and the coating method being the same as described above.

[0142] In the present specification, as drying, a method known in the art, such as air drying, is used.

[0143] In this specification, the steps of rolling and the like subsequent to the steps included in the method for manufacturing a lithium ion secondary battery are known in the art.

[0144] [Example]

[0145] In the following, preferred embodiments will be proposed to facilitate the understanding of the present invention, but the embodiments are only provided to illustrate the present invention. It is obvious to those skilled in the art that various changes and modifications can be made within the scope and technical concept of the present invention, and these changes and modifications naturally fall within the scope of the appended claims.

[0146] <Synthesis Example: Synthesis of Water-Based Adhesive>

[0147] Synthesis example 1

[0148] After acrylamide (AM) and acrylic acid (AA) were mixed at a weight ratio of 40:60 in a reactor equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inflow tube, a polymerization initiator (ammonium persulfate) was added thereto, and the resulting mixture was reacted at 75° C. for 8 hours to prepare a polymer aqueous solution.

[0149] Thereafter, a 0.1 mol NaOH aqueous solution was dropped into the polymer aqueous solution to neutralize the aqueous solution, and then an aqueous adhesive 1 was prepared.

[0150] Synthesis example 2

[0151] Aqueous Adhesive 2 was prepared in the same manner as Synthesis Example 1, except that acrylamide (AM) and acrylic acid (AA) were mixed in a weight ratio of 70:30.

[0152] Synthesis example 3

[0153] Aqueous Adhesive 3 was prepared in the same manner as in Synthesis Example 1, except that acrylamide (AM), acrylic acid (AA), and acrylonitrile (AN) were mixed in a weight ratio of 55:30:15.

[0154] Synthesis example 4

[0155] Aqueous Adhesive 4 was prepared in the same manner as Synthesis Example 1, except that acrylamide (AM) and acrylic acid (AA) were mixed in a weight ratio of 80:20.

[0156] Comparative Synthesis Example 1

[0157] Comparative Adhesive 1 was prepared in the same manner as in Synthesis Example 1, except that acrylamide (AM) and acrylic acid (AA) were mixed in a weight ratio of 5:95.

[0158] Comparative Synthesis Example 2

[0159] Comparative Adhesive 2 was prepared in the same manner as in Synthesis Example 1, except that acrylamide (AM) and acrylic acid (AA) were mixed in a weight ratio of 85:10.

[0160] Comparative Synthesis Example 3

[0161] Comparative Adhesive 3 was prepared in the same manner as in Synthesis Example 1, except that acrylamide (AM), acrylic acid (AA), and acrylonitrile (AN) were mixed in a weight ratio of 25:60:15.

[0162] Comparative Synthesis Example 4

[0163] Comparative Adhesive 4 was prepared in the same manner as in Synthesis Example 1, except that styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) were mixed at a ratio of 2:1.

[0164] <Preparation Examples 1 to 3: Preparation of Pre-dispersion Liquid>

[0165] Single-walled carbon nanotubes (SWCNTs) (manufactured by OCSiAl, Tubll) were used as conductive materials, to which a nonionic vinyl compound polyvinylpyrrolidone (PVP) (manufactured by Zhangzhou Huafu Chemical Co., Ltd., K15) was added as a dispersant, and tannic acid (manufactured by Sigma-Aldrich) was added as a viscosity regulator, and then SWCNT:PVP:tannic acid were mixed in a weight ratio of 1:1:0.4, and the resulting mixture was dispersed (mixed once) using a high shear in-line mixer.

[0166] After that, a pre-dispersion liquid (secondary mixing) having a specific dispersed particle size and a solid content of 1 wt % was prepared by repeatedly circulating the mixture 5 times while adjusting the pressure using a high pressure homogenizer (manufactured by Micronox, model name: PICOMAX). The dispersed particle size of the single-walled carbon nanotubes was measured using a particle size distribution measuring device manufactured by Malvern Panalytical Ltd. The results are shown in Table 1 below.

[0167] The single-walled carbon nanotube (SWCNT) and the dispersant were mixed at a ratio shown in Table 1 below (based on a weight ratio (wt %) relative to 100 wt % of the negative electrode composition).

[0168] <Examples and Comparative Examples: Production of Negative Electrode>

[0169] As shown in Table 1 below, a solvent (water) was added to each negative electrode composition in consideration of coating properties and solid content, and the resulting mixture was stirred to prepare a negative electrode slurry.

[0170] [Table 1]

[0171]

[0172]

[0173] <Experimental example: battery characteristics experiment>

[0174] A copper foil with a thickness of 15 μm was coated with each negative electrode slurry shown in Table 1 and dried to form a negative electrode active material layer with a thickness of 48 μm on one surface of the copper foil. The copper foil was then punched into a circle with a diameter of 14 Φ (mm) to prepare a test negative electrode.

[0175] A 0.3 mm thick lithium foil was used as the positive electrode, a 0.1 mm thick porous polyethylene sheet was used as the separator, and LiPF as a lithium salt was dissolved in a mixed solvent of fluoroethylene carbonate (FEC) and diethyl carbonate (DEC) at a volume ratio of 7:3 at a concentration of about 1 mol / L. 6 The product obtained by reacting lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was used as the electrolyte.

[0176] The negative electrode, the positive electrode, the separator, and the electrolyte were sealed in a stainless steel container to produce a coin cell for evaluation having a thickness of 2 mm and a diameter of 32 mm.

[0177] [Table 2]

[0178] serial number Experimental Example 1: Initial Efficiency (%) Experimental Example 2: Capacity retention rate (%) Example 1 91.5 83 Example 2 91.8 87 Example 3 90.7 81 Example 4 93.1 85 Example 5 91.7 85 Example 6 93 86 Comparative Example 1 91.0 65 Comparative Example 2 90.2 66 Comparative Example 3 90.2 51 Comparative Example 4 93.0 56 Comparative Example 5 91.5 68 Comparative Example 6 93.7 71 Comparative Example 7 91.4 67 Comparative Example 8 93.2 74 Reference Example 1 91.8 76 Reference Example 2 93.0 71

[0179] - Initial efficiency (%): The button cell was charged at a constant current of 0.05C until the voltage reached 0.01V, and discharged at a constant current of 0.05C until the voltage reached 1.5V, and the discharge capacity and initial efficiency were obtained and displayed as the value of (discharge capacity / charge capacity)×100(%).

[0180] -Capacity retention (%): The capacity retention test was performed by charging the button cell at a constant current of 0.05C until the voltage reached 0.01V, discharging the button cell at a constant current of 0.05C until the voltage reached 1.5V, and performing cycle characteristics at a constant current of 0.2C in the same voltage range as above, and calculated based on 30 cycles.

[0181] As shown in Table 2, in Examples 1 to 6, an aqueous binder containing 30 wt% or more and 80 wt% or less of (meth)acrylamide based on the entire aqueous binder was used, and a nonionic vinyl compound (PVP) was used as a dispersant. As a result, all initial efficiencies exceeded 90%, and all capacity retention rates showed 80% or more.

[0182] In contrast, despite the use of a nonionic vinyl compound as a dispersant, Comparative Example 5 achieved a high initial efficiency of 91.5% using an adhesive having a (meth)acrylamide content outside the scope of the present invention (i.e., 30 wt % or more and 80 wt % or less relative to 100 wt % of the total aqueous adhesive), but showed a capacity retention rate of 68%.

[0183] In addition, although a nonionic vinyl compound was used as a dispersant, since Comparative Example 7 used a binder that was a mixture of styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) that did not contain (meth)acrylamide, a high initial efficiency of 91.4% was achieved, but a capacity retention rate of 67% was shown.

[0184] Furthermore, despite using an aqueous binder having a (meth)acrylamide content satisfying the range of the present invention, Comparative Example 8 did not use a nonionic vinyl compound as a dispersant and thus achieved a high initial efficiency of 93.2%, but showed a capacity retention rate of 74%.

[0185] In addition, all of Comparative Examples 1 to 4 and 6 not only used an adhesive having a (meth)acrylamide content of not less than 30 wt % and not more than 80 wt % relative to 100 wt % of the total aqueous adhesive, but also used a cellulose dispersant instead of a nonionic vinyl dispersant, and thus showed a high initial efficiency of over 90%, but Comparative Examples 1 to 4 and 6 showed capacity retention rates of 65%, 66%, 51%, 56% and 71%, respectively.

[0186] Therefore, considering Comparative Examples 5 and 7, it can be seen that when the (meth)acrylamide content of the aqueous binder is outside the range of 30 wt % or more and 80 wt % or less, the influence on the capacity retention rate is as great as if no (meth)acrylamide is contained.

[0187] Moreover, it can be seen that when comparing Comparative Example 5 with Comparative Example 8, the (meth)acrylamide content factor has a greater impact on improving the capacity retention rate than the dispersant factor, and it can be seen from Comparative Examples 1 to 4 and 6 that when the above two factors are not met, the deterioration of the capacity retention rate becomes serious.

[0188] Comparing Reference Examples 1 and 2 with Examples 1 and 4, it can be seen that there is a difference in capacity retention rate depending on whether the particle size distribution range of the single-walled carbon nanotubes of the present invention is met.

Claims

1. A negative electrode composition for a lithium ion secondary battery, comprising: a negative electrode active material; a conductive material; and an aqueous binder, in, The conductive material comprises a pre-dispersion liquid containing single-walled carbon nanotubes (SWCNT) and a dispersant, The aqueous adhesive contains 30% by weight or more and 80% by weight or less of (meth)acrylamide (AM) relative to 100% by weight of the entire aqueous adhesive, and The dispersant includes a nonionic vinyl compound.

2. The negative electrode composition according to claim 1, wherein The negative electrode active material includes one or more selected from the group consisting of silicon-based active materials and carbon-based active materials.

3. The negative electrode composition according to claim 2, wherein: The silicon-based active material contains SiO with x = 0 x , SiO with 0 < x < 2 x , one or more of SiC and Si alloys.

4. The negative electrode composition according to claim 2, wherein: When the negative electrode active material consists only of a silicon-based active material, the silicon-based active material contains one or more selected from the group consisting of SiO where x = 0 x and SiO where 0 < x < 2 x , and based on 100 parts by weight of the silicon-based active material, contains 70 parts by weight or more of SiO where x = 0 x .

5. The negative electrode composition according to claim 2, wherein: The carbon-based active material includes at least one selected from the group consisting of artificial graphite, natural graphite, hard carbon, and soft carbon.

6. The negative electrode composition according to claim 2, wherein: When the negative electrode active material includes a silicon-based active material and a carbon-based active material, a weight ratio of the silicon-based active material to the carbon-based active material is 2:98 to 30:

70.

7. The negative electrode composition according to claim 1, wherein The nonionic vinyl compound includes one or more selected from the group consisting of polyvinyl pyrrolidone (PVP) and polyvinyl butyral (PVB).

8. The negative electrode composition according to claim 1, wherein The aqueous adhesive is a copolymer including (meth)acrylamide (AM) as a first repeating unit and (meth)acrylic acid (AA) as a second repeating unit.

9. The negative electrode composition according to claim 8, wherein The aqueous adhesive is a copolymer further comprising (meth)acrylonitrile (AN) as a third repeating unit. 10 . A negative electrode slurry comprising the negative electrode composition according to claim 1 and a solvent.

11. A negative electrode comprising: a current collector layer; and a negative electrode active material layer disposed on one surface or both surfaces of the current collector layer, wherein: The negative electrode active material layer comprises the negative electrode slurry according to claim 10 or a dried product thereof.

12. A lithium ion secondary battery comprising: a first electrode; a second electrode; a separator interposed between the first electrode and the second electrode; and Electrolytes, Wherein, any one of the first electrode and the second electrode is the negative electrode according to claim 11.

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